Be sure to include a <script> tag reference to jquery.MultiFile.js or jquery.MultiFile.pack.js.

Note the parameters to the Html.BeginForm method. The form must be submitted via an HTTP POST (The FormMethod.Post argument specifies this); and the encoding type should be "multipart/form-data". This is required even when not using jquery.MultiFile.js.

Specify an id and name attribute for the <input type='file' /> element. This is required even when not using jquery.MultiFile.js.